I have the following code :
string excelConnectionString = @\"Provider=Microsoft.Jet.OLEDB.4.0; Data Source=C:\\db\\suc.xls; Extended Properties=\"\"Excel 1
// SET A CONNECTION WITH THE EXCEL FILE.
OleDbConnection myExcelConn = new OleDbConnection
("Provider=Microsoft.ACE.OLEDB.12.0; " +
"Data Source=" + Server.MapPath(".") + "\\" + fileUpload1.FileName +
";Extended Properties='Excel 12.0;HDR=YES'");
Putting Single quote in Extended Properties like Extended Properties ='Excel 12.0:HDR=YES' solved my problem.